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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

I've been brainstorming a simple (I.e. Non-electronic) parachute deploy system that could be easily integrated into a 2l rocket. Would love any feedback or advice from others.

I've tried weighting the nose cone to encourage it to slip off during deceleration/apogee. It turned out to be unreliable and we ended up with quite a few lawn-dart landings... The cone had a very loose fit such that inverting the rocket would cause the cone to fall off. It appears that the air pressure held the cone to the rocket. I expect that increasing the drag on the rocket body may help this, however this leads to another problem...

A second system tried involved adjusting the weight balance of the rocket to behave like a backglider, but with an air flap mounted to the lip of the nose cone. The thought being the flap would offer minimal resistance during launch, but offer greater resistance through apogee and descent. The flap would act to lever the cone off the body deploying the chute. The cone again had a loose fit such that even the weight of the chute would pop the cone off if inverted while stationary. We had a great record with this deploy method even while reducing the flap size to minimal. The main issue was during higher pressure launches, the cone would sometimes be ripped off/lifted off during launch shortly after burnout. We ended up with many early deployments and one shredded chute Our next test will be to snug the cone up a bit and test with different flap sizes to find he optimum balance between minimal drag during launch and ease of deployment.

I'm intrigued by the idea of using only air resistance to remove the cone. I have seen more involved deployment mechs using large flaps, etc to open the chute bay. I like the idea of using something that is elegant in it's simplicity

@addstogether2 I don't rely on the ACR Side Deploy anymore, mainly because its difficult to fix (assuming that you also use cardboard, not corriflute). I usually use my own alteration of the Axial Deploy (USWR)

1. Instead of curved lobes I used five 1x4in strips in the nosecone. I followed the pattern of the lines in a Coke bottle (the bottle has 10 lines). Unfortunately I had to use 2 bottles instead of one.
2. I used sponge instead of bottle rings (although weaker, it can still eject the 'cone). A 65mm version would use the "rubber band bridge", two rubber bands running across the circumference, taped in the middle. Just imagine a slingshot.
3. I use tomy timers. And the timers are mounted externally.

Another pretty dank late reply: Not my video, but I have based a design off of this dude's parachute deployment mechanism.

As a bit of story-time...
I decided to participate in the Science Olympiad Egg-O-Naut Challenge , and so I thought that developing a system to recover an egg would be easy. In short, it was not and I have a decent portion of a journal/log filled with my experience on the development throughout the season with diagrams and descriptions of how the flights went (wrote in that same log for the next season, which featured an altimetry based challenge - I have a special design that I might post at a later date). It was a fair challenge - until I found this video. I basically had my hand at developing a replica of the rocket, and it was fairly successful. This was when I first started to play with bottle rockets with an in-depth mindset.

Anyway, in your case, you don't really need to worry about an egg (unless that's what you're going for) and so you could potentially modify it to your liking.

Sorry for reviving a year-old post, but I felt like this is a necessary contribution to the thread.